This invention relates particularly to data evaluation equipment and procedures for the monitoring and management of brain injuries in mammals.
The brain can be compromised by a number of adverse influences during all stages of life including perinatal asphyxial and hypoperfusion insults, strokes, traumatic brain injuries, cardiac arrest, cardiac bypass surgery, poisoning, and subarachnoid haemorrhages. Considerable variation occurs in the degree and distribution of neuronal loss depending on the type and severity of the injury to the brain.
Injury results in two recognised phases of neuronal loss (see FIG. 16 of the. accompanying figures): primary neuronal death is associated with the insult itself, and delayed neuronal death occurs during a secondary phase some hours later, when a complex pathological cascade of events leading to neuronal death follows the initial injury. A transient insult, such as hypoperfusion, can cause brain cells to die in two phases. The primary phase extends throughout the insult and the early regeneration/reperfusion period. Processes contributing to this primary phase include intracellular Na+ and Ca2+ accumulation, cytotoxic edema, membrane damage, free radicals, and excitotoxicity. However, many neurons do not necessarily die during the primary phase but cytotoxic mechanisms are triggered that lead to a further or delayed death of neurons some hours later. The mechanisms involved in delayed neuronal death are thought to include excitoxicity, seizures, apoptosis, and microglial activation.
Recent studies suggest that it is possible to interfere with these mechanisms and thereby rescue susceptible neurons. Biophysical measures of the pathophysiologic processes preceding and during the phases of neuronal death are likely to prove useful for identifying those patients who may benefit from neuronal rescue therapies. Several clinically relevant factors such as pre-existing injuries, hypotension or metabolic. status may sensitise and alter the response of the brain to injury. Several biophysical parameters recorded during and after an insult are generally needed to reliably discriminate the present phase of injury and periods of cytotoxic activity.
The monitoring of patients with brain injuries whether caused by externally induced trauma such as birth or accident or by circulatory problems or poisoning has hitherto relied upon clinical signs but these may not be observable until a time at which the damage may have become irreversible. Neurological examination is of limited value (in particular for those on life support apparatus) for predicting outcome and determining the phase of injury. Similarly, use of imaging techniques such as MRI and CT are not practical for monitoring evolving injuries in these patients.
The invention provides an intelligent monitoring instrument, termed a brain rescue instrument or monitor, and method, for monitoring, identifying and guiding the application of brain therapies to patients, with evolving brain injuries, and generally for assisting with the management and treatment of brain injury in a mammalian patient.
In broad terms in one aspect the invention comprises an intelligent brain rescue instrument for identifying, monitoring, and guiding the application of brain therapies to patients with evolving brain injuries, comprising:
input means for acquiring a multiple number of signals each indicative of a different biochemical or biophysical parameter of a patient, and
computing means configured to continuously sample and process each of the acquired signals and display to a user on a monitor at least some of the parameters, the displayed parameters being selected by system software embodying expert analytical rules as the most significant parameters or as parameters having values indicative or predictive at any time of actual or potential future deterioration of the brain state of the patient.
In broad terms in another aspect the invention comprises an intelligent brain rescue instrument for identifying, monitoring, and guiding the application of brain therapies to patients with evolving brain injuries, comprising:
I) input means for acquiring a set of a multiple number of signals each indicative of a different biochemical or biophysical parameter of the patient, said set of signals being selected from:
(a) an EEG signal;
(b) an ECG signal;
(c) a signal indicative of brain tissue impedance of the patient;
(d) signal or signals indicative of the temperature of the patient;
(e) signals indicative of the arterial blood pressure and/or arterial oxygen saturation, of the patient;
(f) a signal indicative of intracranial pressure;
(g) a signal or signals indicative of any of cerebral blood flow, cerebral blood volume, cerebral oxygenation, or cerebral metabolite measures;
(h) a signal or signals indicative of systemic glucose concentration and/or central glucose concentration;
(i) a signal or signals indicative of systemic lactate concentration and/or central lactate concentration;
(j) a signal indicative of cerebrovascular status;
(k) a signal indicative of cerebral cytochrome levels;
(l) a signal indicative of the patient""s heart rate;
(m) a signal indicative of central cytotoxic activity;
(n) a signal or signals indicative of movement or muscle activity;
(o) a signal or signals indicative of any other biochemical or biophysical parameter useful as indicative of the current or as predictive of the future brain state of the patient; and
II) computing means configured to:
(a) continuously sample and process each of the acquired signals; and
(b) display to a user on a monitor information a selected subset of the acquired parameters, said selected subset of parameters which is displayed being selected either by system software embodying expert analytical rules as the most significant parameters or as parameters having values indicative or predictive at any time of actual or potential deterioration of the brain state of the patient, with said parameters being displayed against a scale or scales or in a way which highlights to a clinician any variations of the parameters indicative or predictive of the deterioration of the brain state of the patient, or alternatively being override selected at any time by the user.
In broad terms in a further aspect the invention comprises a method for identifying, monitoring, and guiding the application of brain therapies to patients with evolving brain injuries, comprising acquiring a multiple number of signals each indicative of a different biochemical or biophysical parameter of a patient, and via computing means continuously sampling each of the acquired signals and displaying to a user on a monitor at least some of the parameters, the displayed parameters being selected by system software embodying expert analytical rules as parameters having values indicative or predictive at any time of actual or potential future deterioration of the brain state of the patient, with said parameters being displayed against a scale or scales or in a way which highlights to a clinician variations of the parameters indicative or predictive of deterioration in the brain state of the patient.
The brain rescue instrument monitors at least some of the pathophysiologic and temporal events surrounding encephalopathies - which events are predictive of pathological neuronal death or can influence the degree of secondary injury. This information is a prerequisite to deciding whether or not intervention with neuronal rescue therapy is indicated. The invention enables a better detection procedure for predicting the secondary loss of brain cells, so that steps to alleviate secondary injury may be taken as soon as possible and even before the appearance of clinical signs, to achieve increased survival and better long-term prospects of patients.